1. Field of the Invention
This invention relates to exercise machines, such as bicycling, rowing, and skiing simulators, and weight or elastic based lifting machines.
2. Prior Art
Exercise equipment takes many forms: free weights; rowing, skiing, and bicycling simulators; weight and elastic tension based machines. Each provides a work load and some means to judge the amount of work performed.
Free weights are effective for non-aerobic exercise. A measure of the work performed in a given weight-training program can be derived from the number of lift repetitions at each weight. However, a lifter's form and limb length determine the amount of work done in each repetition, so different lifters can expend different amounts of energy on identical programs. The form of a lifter can vary over time. These unknown variables make work measurement both inaccurate and inconsistent.
A major disadvantage of free weights is safety. If a grip slips, the weights drop, creating a hazard. Some weight stands can topple if the weights are set down carelessly, which is likely when exhaustion is reached. Another hazard occurs if a lift cannot be completed. Assistance is then needed or the weights must be thrown aside. These conditions can result in serious injury. Changing weights is inconvenient, especially when two lifters of different strengths alternately use the same bar. The inherent weight of any weight-based-equipment is a disadvantage in shipping and moving. Weights are noisy--a major disadvantage in multi-story buildings and dense residential installations.
Some of these disadvantages are absent in machines that work with elastic tension. However, work measurement is similarly inaccurate. Safety is better, but the mechanism can recoil if the grip slips, causing injury.
Equipment using resistance from friction or pneumatics, such as bicycling, skiing, and rowing simulators, have poor ability to measure work. Measurement of speed and miles `traveled` is sometimes offered, but not the most significant quantity--work performed. A work calculation requires knowledge of the power input or resistance overcome, but these quantities are not measured.
Theoretically, one does not need to know the amount of work accomplished in a given exercise session. But when an effort cannot be measured, it becomes much less meaningful for most people, and harder to motivate. A known goal, and a way to measure progress, are basic components of motivation. This is enhanced if progress can be graphically displayed continuously during the effort.